Something To Consider...

Discussion in 'Conservation' started by Klickrolf, Nov 8, 2016.

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  1. Klickrolf

    Klickrolf Active Member

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    Salmo Salar and steelhead life histories are very, very, very, very similar.

    Why aren't we doing this in the PNW for steelhead? The egg part...


    I stole this from speypages.com
     
    Last edited: Nov 8, 2016
  2. jeff bandy

    jeff bandy Make my day

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    Darn good question. It's not a new idea. Similar methods have been used to establish populations of brown trout were stocking failed.
     
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  3. Salmo_g

    Salmo_g Well-Known Member

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    Planting eyed steelhead eggs in selected tributary streams has been tried in the PNW. We didn't have the hydraulic machine that is shown in the Saco video, but that wouldn't have mattered. In the 1970s a some of us thought it would be a good idea to try the Vibert box as a means of planting eggs in streambed gravel. The Vibert box is a small plastic grid box made up of two chambers, a small one for eggs and a larger one to contain selected clean gravel for fry to drop into while they grow from the hatch to emergent fry stage.

    The projects failed miserably. It's hard to find a stream in the PNW that has no logging or other land use that doesn't produce silt whenever it rains. One rainstorm freshet in the selected creeks and the Vibert boxes became completely choked with silt, suffocating the eggs.

    Aside from not producing any viable fry, the method of planting eggs in stream gravel is very labor intensive and costly for the number of smolts produced. Using the Saco numbers as an example and substituting common, even optomistic, steelhead survival numbers let's see what we get:

    35,000 eggs x 0.12 egg to fry survival x 0.1 fry to smolt = 420 smolts x 0.1 smolt to adult survival = 42 adult salmon or steelhead. I didn't notice if the video indicated the source of the broodstock and eggs used in the program. That would be an important consideration.

    It looks like the Saco program uses a combination of volunteer and agency staff. It would be useful to know what the total agency cost and volunteer man-hours are required for the results they get.

    Another extremely important point is having usable habitat available. The Saco program notes that they planted the eggs in an area that had spawning and rearing habitat that was unused due to five beaver dam blockages. I don't know about Maine, but in western WA, if you removed five beaver dams and come back two weeks later, the beavers will have re-built those dams. Around here, the ecological relationship between beavers and salmon is a dynamic one. In western WA we generally don't have steelhead habitat that isn't already being used. Stocking eggs would be to super-impose additional fish on habitat that is already occupied and producing juvenile steelhead at the current level of habitat productivity. All one could expect in that case is either no change or a slight decrease in overall smolt production.

    Some things that seem like a good idea don't always turn out to be quite what one expected.

    Sg
     
  4. jeff bandy

    jeff bandy Make my day

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    ?
     
  5. Yard Sale

    Yard Sale Huge Member

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    I believe he is speaking of carrying capacity.

    SG, how is CC established and how many of our rivers are at it?
     
  6. Salmo_g

    Salmo_g Well-Known Member

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    YS,

    Right, about carrying capacity.

    First let's define carrying capacity (CC). CC is the maximum number of a species that a given habitat can support, or produce annually. This would be an average, as inter-annual variations are expected due to floods, drought, and other factors.

    I don't establish CC, but I would estimate it by analyzing spawner-recruit and harvest data. That data informs us of how many recruits are produced by varying numbers of spawners. (A recruit is a fish in the subsequent generation that survives to either contribute to harvest or spawning escapement.) A number of years of data are needed, and the number of spawners needs to vary over that time period.

    Beginning from the low end, as the number of spawners goes up, the number of recruits also goes up; i.e., more spawners equals more recruits. It does, that is, until the carrying capacity is reached. When capacity is reached, increasing the number of spawners no longer results in an increased number of recruits.

    Using the somewhat data-rich example of the Skagit again, we have observed spawning escapements ranging from a low of 2,500 in 2009 to 16,000 in 1988. With the lower escapements you generally get a larger runsize four years later (even after accounting for the observed range of year classes). But somewhere between 8,000 and 9,000 spawners and up, four years later you get a runsize (recruits) that is smaller than the escapement that produced it. That's because the larger escapements seed the available habitat with more eggs and fry then that habitat has the capacity to support. Hence, CC has been reached.

    Because harvest is so severely restricted in PS rivers, and has been for a sufficient number of years, IMO all PS rivers are producing wild steelhead at their current CC. How could they not be? If harvest isn't causing under-escapement, every watershed is able to increase its steelhead population as long as spawners are able to replace themselves or produce a surplus.

    One way they could not be is when PS marine conditions cause a large % of smolts that leave river mouths to not survive the migration out of the Sound and into the ocean. A lot of river have had S:R ratios of less than one even when the number of spawners was low. If that were a permanent condition, then runs would become functionally extinct over a period of several generations. We know from past population performance that the PS factor hasn't always limited populations the way it has recently until the last couple years.

    Except for conditions like whatever has been constraining PS steelhead populations since the 1990s, I'd postulate that all WA rivers downstream of Bonneville Dam on the Columbia, coastal, and PS river are at their current carrying capacities. There might be a few exceptions where harvest in some years is causing escapement to be less than is necessary for fully seeding habitat.

    Sg
     
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  7. jeff bandy

    jeff bandy Make my day

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    Isn't that saying (and I'm really reaching here) that almost all of the problem with low steelhead numbers can be attributed to ocean conditions and over harvest in the oceans.
     
  8. Salmo_g

    Salmo_g Well-Known Member

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    Jeff,

    No, because what I posted above is only part of the story. I mentioned that PS steelhead rivers are at their current carrying capacity, with the emphasis on "current." Historical steelhead populations are variously estimated at having been 5 to 10 times larger than at present. That may have been due to higher ocean survival a century ago, but it is most definitely due in large part to the very severe degradation of habitat that has so significantly reduced both productivity and capacity.

    IMO, most of that productivity and capacity isn't coming back, no matter how much some of the fish recovery folks may wish or want it to.

    Sg
     
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  9. Klickrolf

    Klickrolf Active Member

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    I think it's worth a try in a few Columbia tribs above Bonneville. Very confident the drainage I call home sits no where near CC. If the same number of adults return to spawn each year it's because spawner escapement is limited by freshwater harvest and unlimited C&R. Maybe our winter run is immune but not the spring, summer & fall runs. Egg boxes wouldn't work here but I think hydraulic redd creator's might. We need more fish to think or act like wild fish before they head to the salt.
     
  10. SilverFly

    SilverFly Active Member

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    Sg, I'd be very interested in your thoughts on what the key habitat differences might be in these rivers regarding their current carrying capacity vs historical. If for no other reason than to dispel any uneducated hunches on my part.

    Specifically, that when these rivers were turned into single channel log flumes, the loss of braided/multi-channel hydrology massively reduced the volume of rearing habitat.

    While I'm sure there are a host of other factors involved, such as current speed, water temp, DO content, gravel scouring, riparian vegetation, etc.. etc.. I can't help but think that the sheer loss of physical space for juvenile fish to live and feed in, isn't the primary limiting factor to CC in single channel streams. Is there any comparative data on CC in single channel vs multi/braided channel watersheds?

    Another thought I've had that may be more relevant to PS streams, are changes that have occurred in the "transitional" marine environment (if that's the right term). One key difference that comes to mind with PS today vs historically, is the loss of kelp beds. Having been to places like Barkeley Sound which are literally choked with kelp today, I would assume more closely resemble what PS looked like many decades ago. If so, and assuming the loss of kelp in PS has had an adverse on marine survival rates, then could that in itself be considered a loss of CC?

    Hopefully that makes some sense.
     
    Last edited: Nov 13, 2016
  11. Matt B

    Matt B ...

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    SF, you didn't direct your question to me, but I am familiar with salmon recovery issues in a couple of Puget Sound watersheds, and have a decent understanding of limiting factors for anadromous fish productivity in others. Based on the work that I have seen or been a part of, your hunch is correct. We've disconnected or outright destroyed large quantities of floodplain and tributary habitats in these watersheds. The various species use the habitats differently, but whether its floodplain connectivity that "absorbs" otherwise scouring flows, or direct juvenile rearing habitat, the loss of early emergence refuges and rearing space creates a freshwater habitat bottleneck that is limiting anadromous productivity. In some watersheds, you can add in the altered hydrograph due to increased impervious area and deforestation of headwaters, not to mention pollution, summertime water withdrawals, etc. etc. that exacerbate the problem.
     
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  12. Salmo_g

    Salmo_g Well-Known Member

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    SilverFly,

    I think the two most obvious changes affecting habitat are logging and forest roads. These two attributes cause a huge change to the watershed hydrograph and vastly increased sediment releases and rate. The former also causes and contributes to modified stream channel morphometrics, which as you suggest, reduces the quantity and quality of spawning and rearing habitat.

    At the lower ends of watersheds, roads and agriculture and rural and urban development has caused or directly forced single channels where braided were once common. I don't know of any comparative data that examines this directly, but if you're familiar with the Weighted Usable Area (WUA) concept of the Instream Flow Incremental Method, the model generally calculates more WUA per unit area of stream across braided channels than across a single channel because more of the channel cross section fits the higher points on the WUA curve. I think the direct comparison could be made; I just am not familiar with any study that looks at that.

    Oh yeah, we the hell did the kelp go? Beats me, but kelp beds in PS are like LWD in streams for creating more habitat niches for fish. The loss of kelp beds has to decrease both productivity and capacity for a lot of species.

    Matt B.,

    Yes, you hit on major causes of reduced habitat productivity and capacity.

    Sg
     
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  13. freestoneangler

    freestoneangler Not to be confused with Freestone

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    So is there a point where habitat loss and subsequent carrying capacity reaches a critical point and fishing, by any method, should not be allowed? Historical vs. current CC, as noted, is significant. From the discussion, it sounds like there is little argument that habitat is still being lost... in spite of the more recent decades of throttling the past trashing of watersheds. At what point do we just stop fishing them?
     
  14. Salmo_g

    Salmo_g Well-Known Member

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    Yes, there is such a point. The logical trigger for suspending all fishing activity would be when fishing is a factor limiting abundance. Prohibiting fishing when it isn't limiting a population would just be a feel good measure. But there are a lot of interests that prefer feel good measures, like those proposing MPAs (Marine Protected Areas) for PS rockfish, even though the regulations adopted by WDFW are even more effective in conserving rockfish.

    There are BC steelhead runs as low as 200 fish or so where fishing is still allowed. Because the run sizes are so low, there is not a lot of fishing activity, and the fishing (all CNR) that does occur isn't limiting the population abundances. Habitat productivity and capacity is the limiting factor. These populations occur in watersheds that have been subjected to horizon to horizon clear-cut logging and forest road building, so the habitat has been trashed. Even with enlightened, multi-purpose forest management, those rivers won't ever recover to their historical productivity.
     
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  15. Matt B

    Matt B ...

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    Yeah, what happened to the kelp beds in Puget Sound? Seems to me that bulkheading wouldn't affect kelp the way it might eelgrass, but I'm really just guessing at this. Someone told me that purse seiners had something to do with it since they can't fish in the kelp beds, but I'm not sure how they would actually do that.
     
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